The spinal column is comprised of twenty-six interlocking vertebrae. These vertebrae are separated by disks. The spine provides load-bearing support for one-half of the body's mass and it protects the nerves of the spinal column. The disks provide shock absorption and facilitate the bending of the spine.
The combination of the vertebrae and disks at each vertebral segment allows for motion of the spine, in particular, flexing, rotation and extension. The motion and support functions of the spine, in combination with the many interlocking parts and nerve roots associated with the spinal column, can result in back pain due to various reasons. Such back pain may result from the degeneration of disks due to age, disease, or injury. Further, vertebral bodies may be compromised due to disease or defects, such as a tumor, or injury, such as fracture.
In certain cases, it may be necessary to remove or replace one or more of the vertebral bodies or disks to alleviate pain or regain spinal functionality. Replacement of a vertebral body is typically required due to an unstable burst fracture, severe compression facture, or tumor decompression.
A vertebral body replacement procedure typically involves the removal of the disks above and below the compromised vertebral body along with all or a portion of the vertebral body. In place of the removed elements, a strut graft and plate are used make the vertebrae above and below the replaced vertebral body grow together and become one bone. Because the intention of a spinal fusion procedure utilized along with vertebral body replacement is to create solid bone in the area that is excised, the spacer that is inserted to restore normal height may be configured to enhance bone in-growth, which may be enhanced by the addition of bone growth material.
In a vertebral body replacement procedure, the vertebral body is partially or entirely replaced by a vertebral prosthesis. Several vertebral prosthesis designs are known in the art. One such vertebral prosthesis design is shown in U.S. application Ser. No. 10/686,998, titled “Vertebral Prosthesis,” which is incorporated by reference herein in its entirety.
When a vertebral prosthesis is utilized to replace a vertebral body, a spinal fixation system may be utilized to stabilize the adjacent vertebrae. Such a spinal fixation system may include a plate designed to be attached to the adjacent vertebrae with bone screws to lock the adjacent vertebrae into position relative to one another. The spinal fixation system may be utilized because the vertebral prosthesis is not configured to provide the stability necessary for fusing the prosthesis with the adjacent vertebrae.
The use of a vertebral prosthesis along with a supplemental spinal fixation system presents certain challenges. Depending on the load carried by the vertebral prosthesis, the prosthesis can collapse into the adjacent bone. Further, the bone screws utilized to attach the spinal fixation plate to the adjacent vertebrae may migrate over time, decreasing the effectiveness of the spinal fixation.
It would be advantageous to provide a vertebral body replacement system that includes a vertebral prosthesis and spinal fixation system that are designed to work in conjunction with one another to address one or more of the above identified challenges presented by current systems. It would also be advantageous to provide a vertebral body replacement system that may be utilized without a supplemental spinal fixation system while still providing the spinal fusion functionality.
It would be desirable to provide a system and/or procedure that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-identified needs.